Crankcase ventilation system



April 24, 1962 w. o. THOMPSON CRANKCASE VENTILATION SYSTEM 5 Sheets-Sheet 1 Filed Sept. 22, 1961 INVENTOR: WILL/AM 0. F/OMPSOAI BY 56 4 Z ATTORNEYS April 1962 w. o. THOMPSON 3,030,942

CRANKCASE VENTILATION SYSTEM Filed Sept. 22, 1961 5 Sheets-Sheet 2 INVENTOR. Mil/14M 0. momma/v A TTOAWEVS April 24, 1962 w. o. THOMPSON 3,030,942

CRANKCASE VENTILATION SYSTEM Filed Sept. 22, 1961 3 Sheets-Sheet 3 IN VENTOR. Wax/4M 0. 7Z/0MA504 821% w fly;

United States Patent 3,030,942 CRANKCASE VENTILATION SYSTEM William 0. Thompson, 1712 Kearny St, San Francisco, Calif. Filed Sept. 22, 1961, Ser. No. 140,975 4 Claims. (Cl. 123-119) This application is a continuation-in-part of my application Serial No. 44,383 filed July 21, 1960.

This invention relates to an internal combustion engine air pollution control device. More particularly, it relates to a device for scavenging the crankcase effluent and returning it for burning to the engine of a motor vehicle.

It is recognized that emission of pollutants from motor vehicles is a major contributor to air pollution in many areas. Control and elimination of such pollutants is of prime importance for the protection and preservation of the public health and well being, and for the prevention of irritation to the senses, interference with visibility, and damage to vegetation and property.

The effluent emanating from the crankcase and released to the atmosphere has been variously estimated to be from one-fourth to over one-half of the total pollutants contributed by the motor vehicle. This effluent consists of foul-smelling, noxious oil vapors, toxic carbon monoxide, some harmless water vapor, and unburned hydrocarbons which may synthesize into eye, nose and throat irritants and crop-damaging pollutants. The balance of the emission is mainly attributed to carbon monoxide and unburned hydrocarbons from the engine exhaust, with some evaporated hydrocarbons from the fuel tank and leakage.

It has long been known that it is beneficial to engine operation to pass a continuous stream of fresh air through the crankcase to cool the lubricant and remove diluents such as water vapor and unburned hydrocarbon blow-byproducts. This is most usually accomplished by the installation of a draft tube which is a Pitot tube having a rearward opening to generate a vacuum due to the forward motion of the vehicle. The discharge from this tube is, of course, to the atmosphere in a manner such as to cause air pollution.

It has also been long known that it is beneficial to engine operation to provide extra lubrication to valve stems and guides (upper cylinder oilers) and to introduce water to achieve an endothermic-exothermic reaction (water injection). It is obvious that the recovery and reintroduction to the engine of unburned hydrocarbons and Water vapor will improve the overall economy of operation.

Some devices have been proposed to ventilate the crankcase by utilizing the power in the stream of exhaust gases to create a vacuum for air movement. Again, the efiiuent is disposed to the atmosphere or, in the case of a catalytic mufiler, to add its. contamination and conversion to the work of the catalyst.

Other devices have been proposed to ventilate the crankcase by utilizing the intake manifold vacuum to create air movement. This does reintroduce the effluent to the engine in a beneficial manner and avoids disposal to the atmosphere.

However, the intake manifold vacuum is available in inverse proportion to the creation of blow byproducts in the form of water vapor, carbon monoxide and unburned hydrocarbons. Such devices introduce valves and/or orifices in the line to the intake manifold to reduce or reverse this available vacuum. These restrictive compo nents are necessarily in the effluent line and therefore subject to contamination, with consequent sticking and plugging, thus rendering the device inoperative.

It is among the objects of this invention to provide 3,030,942 Patented Apr. 24, 1962 ice an improved apparatus and method for collecting and eliminating the air pollutants generally emitted to the atmosphere from the crankcase.

Another object is to utilize these crankcase vapors in such a manner as to benefit and improve the operation of the engine, by better lubrication and combustion, so as to reduce the amount of carbon monoxide and unburned hydrocarbons emitted from the exhaust.

Still another object is to return these crankcase vapors for better fuel economy.

A further object is to utilize readily available energy of the primary combustion air stream and induce directly into it, by means of a venturi or suitable device, the crankcase effluent and the added entraining and cooling air so that such volume is introduced outwardly of the fuel mixing venturi(s) and throttle butterfly valve(s), and thus avoid disturbance of engine operation as would be the case if introduced inwardly of such fuel metering devices, in the manner of an inlet manifold leak, resulting in a lean mixture.

A still further object is to utilize this clean, filtered air stream to contain the only valve to control its energy, and thereby avoid the disadvantages of valves and/or orifices in the crankcase effluent line, which might readily become stuck and inoperative.

A still further object is to provide a readily manufacturable, self-contained assembly that can be fitted in the field by unskilled labor to the carburetor and over which the air cleaner neck will fit. No connection need be made below the throttle butterfly which would necessitate drilling the intake manifold or removing the carburetor to introduce an orifice plate with consequent readjustment of automatic transmission linkage, or removal of studs with possible breakage. This is particularly applicable to V8s with 2- and 4-barrel carburetors where there is no plugged or other opening available below the throttle which would not interfere with operation of windshield wiper, vacuum advance, etc.

In the drawings forming a part of this application:

FIGURE 1 is a sectional view of a V-8 engine embodying the device of the present invention.

FIGURE 2 is a side elevation partly in section of one embodiment of the present invention.

FIGURE 3 is a side elevation partly in section of another embodiment of the present invention.

FIGURE 4 is' a plan view of the device shown in FIGURE 3.

FIGURE 5 is a plan view of another device embodying the present invention.

FIGURE 6 is a side view, partly in section, of the device shown in FIGURE 5.

Referring now to FIGURE 1 by reference characters, there is shown an engine generally designated 5 having a crankcase generally designated as 7, which is provided with the usual air breather 9 and draft tube 11. Draft tube 11 would normally be inclined to the rear of the engine as is shown at 13, but, utilizing the device of the present invention, the draft tube is fully or partially plugged at 13. The engine is also provided with the usual air cleaner 15 and carburetor 17. A valve embodying the present invention is shown at 19. Lines 21 and 25 connect the valve 19 to the line 11. If desired, the line may incorporate a filter 23 for trapping entrained liquid. It will be noted that the valve 19 lies entirely Within the horn of the air cleaner 15 and does not add to the height thereof, so that the device can be used in modern cars where limited clearance is available with the hood. Further, since the valve 19 is located above the carburetor 17, there is no interference with the operation of the choke, gasoline venturi or manifolding. Valve 19 may be installed in place without drilling or tapping any hole, it being only necessary to remove the air bypass the venturi.

cleaner, put the valve in place, and restore the air cleaner to its normal position. For installation on dual and single barrel carburetors, having smaller air horns, it may be desirable for reasons of maximum air flow, hood clearance and standardization in manufacture to have only one size valve. This may readily be accomplished by placing the valve in a dry type air cleaner within a suitable housing and replacing the existing oil bath air cleaner. These dry type air cleaners are standard items of cornmercc and are readily available.

In FIGURE 2 there is shown an embodiment of one form of valve of the present invention. The valve has an open frame member 27 which is clamped by means of a nut 29 to the threaded rod 31 which is normally employed to hold the air cleaner in place. The horn of the air cleaner 33 rests on top of the carburetor 35 in the normal manner. Frame member 27 is merely a strap of suitable metal, and thus offers no substantial obstruction to the free flow of air through the air cleaner and carburetor. Suspended within the valve of the present invention is a first flared annular ring 37 mounted over a second ring 39 somewhat larger in inside diameter. Mounted within the two rings is a chimney 41 which may be welded to the frame 27 as at 42. The pipe 21 leads to the annular space 43, between the rings 37 and 39, and it Will be observed that a venturi effect is produced, and that when the air is drawn through the carburetor, additional air will be drawn through the line 21.

Mounted within the chimney 41 is the dome-like valve element 45 which is mounted on the sleeve 47 which is free to slide on the rod 31. A spring 49, normally biases the valve element 45 upwardly, where it seats against the inturned top edge of the chimney 41. Under conditions wherein a relatively small amount of air is flowing through the horn 33 of the air cleaner the element 45 will assume the position shown in solid lines, so that all of the air will pass around the outside of the chimney and contribute to the venturi effect. However, when a large amount of air is flowing through the horn 33, the element 45 will be deflected downwardly into the position shown in dotted lines in FIGURE 2 so that a portion of the air will pass inside of the chimney 41 and will thus Sleeve 47 limits the downward movement. Thus, any reduction in venturi effect, due to diversion of air through the chimney, will be compensated by the nozzle injector effect of this volume of air exiting the chimney just below the venturi exit slots. In this manner, the degree of vacuum in line 21 is maintained almost constant. Thus, under certain engine conditions, such as when the engine is idling, the valve 19 remains closed so that even if the engine is running at a low rate of speed, enough air is drawn through the venturi to assure adequate crankcase ventilation. On the other hand, when the engine is running at a high rate of speed, so that a large amount of air is passing through the horn 33, a portion of the air is bypassed through the inside of the chimney 41, permitting normal engine operation yet assuring an adequate vacuum in the line 21.

In FIGURES 3 and 4, another embodiment of the invention is shown where, instead of using a spring operated valve which slides down the rod 31, a flapper type of valve is employed. Since many of the parts of the valve of FIGURES 3 and 4 are common with those of the valve shown in FIGURE 2, the same numbers have been used for the common parts and only the diflerent parts are herein described. Here, a pair of flapper valve elements 45 and 47 are mounted for rotation on the pins 49 and 51. A counter weight 53 is provided for the element 45 while a corresponding weight 55 is provided for the valve 47. Normally, the counter weight pulls the valves closed, as shown in solid lines in FIG- URE 3 while, if there is a large flow of air through the valve, the flapper elements 45 and 47 are deflected downwardly against the force of the weights, as is shown in 4 dotted lines in FIGURE 3. Extensions on the weights 53 and 55 cooperate with pins 49 and 51 to limit the rotational movement of the flapper elements. Thus, the valve shown in FIGURES 3 and 4 operates in substantially the same manner as the valves shown in FIGURE 2.

An improved design which incorporates the same basic principles of dividing the combustion air stream into two separate channels and then rejoining them ahead of the throttle butterfly is shown in FIGURES 5 and 6. This new design provides a lesser pressure drop across the device so as to lessen horsepower loss, and a lower silhouette so as to fit the later model cars with low hood configurations.

Referring to FIGURES 5 and 6, a carburetor air horn and flange are represented generally at 101, having a cross member 103 to support the stud 105, which with wing nut 107 holds down the lid 109 against the filter 111 against the base plate 113 having a flange 102 which bears securely against the carburetor air horn and flange 101. This base plate has secured to it a flanged ring 115 which receives the valve seat element 117 in an airtight snap fit manner. This flanged ring also acts as a retainer for the spring assembly consisting of three or more leaf springs 119 afiixed to spring ring 121. This spring assembly urges the annular valve element 123 upwardly to seat against the annular opening in the outer valve seat element 117. For clarity, this valve element 123 is shown in a mid-position. The inner seat 116 and outer seat of 117 of the valve element are held together by three or more arms 125. Element 117 may be formed out of one piece by punching out three or more openings 127 in a disc, drawing the disc into the generally indicated cup shape and pinching the arms 125 to give rigidity and lessen resistance to air flow. It will be noted that the valve element 123 is slightly convex and seats well inside and outside the annular openings 127 so that deformations due to the pinching of arms 125 will be avoided and a good closure of the valve will result.

A venturi 129 with slots 131 and annular space 133 is fitted into a sleeve 135 which carries tube 137 (communicating to the crankcase as previously described) which extends through a hole 139 in base plate 113 fitted with a grommet 141. The sleeve 135 extends downwardly to a point below the full open position of valve element 123 so as to prevent turbulent air from entering the base of the venturi and afiecting the partial vacuum being exerted on the crankcase by the normally downward air flow through the venturi. Sleeve 135 is secured to valve seat element 116 and its upper end fitted with an air breather tube 143 reaching beyond the annular openings 127 so that air may reach the venturi without being disturbed by air flowing downward-1y through the openings 127 when valve 123 is unseated. This air breather tube preferably points generally away from the passenger compartment to act partially as a silencer at idle and deceleration. It may be fitted with baflles (not shown) to reduce air flow through the venturi at high speeds and heavy loads without interfering with lower air flows through the venturi at idle and deceleration.

Venturi 129 is of sufl'icient size to permit flow of all air required for idle or induced at deceleration so that valve element 123 is seated against 116 and 117 by spring assembly 119 and this air flow induces a partial vacuum on the crankcase through slots 131, annular space 133, tube 137 and associated suitable fittings and hose. As the throttle is opened and engine demand for combustion air is increased, the diiferential pressure on valve element 123 forces it downward against spring tension and air flows unobstructedly through the central opening of valve element 123, while a suflicient portion continues to flow through the venturi via air breather tube 143 to maintain an increased partial vacuum on the crankcase commensurate with the increased blow-by. Experiments have indicated that a venturi of suflicient size to accommodate full air requirements will induce no vacuum at idle and so much under load conditions that oil will be pulled out of the crankcase. Also, at deceleration there is such turbulence above the throttle butterfly that a reverse flow into the crankcase occurs. while blow-by is minimal at idle and deceleration, it is desirable to maintain a slight air movement to cool the crankcase and to prevent a buildup of oil vapors that would come out the breather cap 9 and prove noxious to driver and passengers.

I claim:

1. A crankcase ventilation system comprising in combination an automobile engine having a carburetor thereon, an air passage ahead of said carburetor, said air passage being divided into first and second parallel paths, a venturi in the first of said paths, a connection between said venturi and the crankcase of said engine, and a valve in the second of said paths, said valve closing when the rate of air flow through said passage is low, an opening under the pressure of air as air flow increases through said passage.

2. The system of claim 1 wherein said two paths are concentric with an annular venturi in the first of said paths and with the second of said paths located inside of said venturi.

3. The structure of claim 2 wherein said venturi has a concentric chimney located inside thereof with said second path inside of said chimney.

4. The crankcase ventilation system of claim 2 wherein said venturi is located at the center of the air passage with the second path surrounding said venturi.

References Cited in the file of this patent UNITED STATES PATENTS 2,274,894 Gray Mar. 3, 1942 2,281,124 Westcott Apr. 28, 1942 2,493,617 Chubbuck I an. 3, 1950 

